I’m not a published reader. My audition got rejected for a noisy mouth. My sound file was perfect—and they said so. Passes ACX-Check and ACX themselves (this was before ACX AudioLab).
That was back when they offered comprehensive Auditions complete with Human Quality Control. Not any more. They offer ACX AudioLab which is their version of ACX-Check. Everything you can do without human intervention. All it does is check the mechanical standards. Where are your peaks, are you loud enough, and how loud is your background noise? Actually, someone said they don’t check noise.
They make you complete the book read with lip smacks, submit it, and then reject you for lip smacks. That’s one reason the post production cleanup tools are suddenly super popular. “Where do I click to get rid of lip smacks—on my whole book?”
We can do some of that short-submission theatrical evaluation here on the forum. There was a recent forum poster with a laundry list of problems. P-Popping, breath noises, background/fan noise, loud music, etc. But unlike Loudness and Noise where you either pass or you don’t, mouth distortion is an opinion and ACX’s opinion is what counts.
They have two additional hurdles. Your book has to be available on Amazon in either paper or eBook before you post your completed read, and they have a published list of unacceptable book types. Scroll down.
https://www.acx.com/help/200878270
I made some minor mistakes in slightly changing the words from the text.
That’s between you and the author. Who is the author? My opinion is they don’t check that.
Their job is to publish valuable works for sale and split off damaged works as quickly as possible. In my opinion, I would look at the ACX Audiolab ratings and check the MP3 compression. Check the silences (room tone) at the beginning and end of each chapter. Check format conformance (chapter headings, attributions, etc), briefly listen to the chapter ends and beginnings, the beginning and the end of the book, and then spot check at random. They’re a business. Checking your book can’t be a career move, and those are the places presenters screw up the most.
There are stupid, right-brain errors. Putting the wrong number of seconds of room tone (silence) before and after each chapter is surprisingly popular. That is a clear, stated requirement.

And then, way down at the bottom of the list, you have to have a pleasant reading voice that doesn’t scare the horses. That’s not to say you have a be a pro announcer. I have several audiobooks by Sarah Vowell.
https://www.kozco.com/tech/audacity/clips/Pro/SaraVowellAssassinationList.mp3
She’s a pleasant storyteller but not likely to be hired to sell coffee.
Koz